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A new conservation result of WKL0 over RCA0

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In this paper we give a partial answer to a conjecture of Tanaka. We prove that: if WKL0 proves a sentence of the form (∀X)(∃!Y)ψ(X, Y) for a Σ0 3-formula ψ, then so does RCA0.

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Received: 12 April 1999 / Published online: 3 October 2001

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Fernandes, A. A new conservation result of WKL0 over RCA0. Arch. Math. Logic 41, 55–63 (2002).

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  • Partial Answer
  • Conservation Result